Take them to a auto store and they will measure them and more than likely they will turn them down. I have had 50 Mercedes cars and have done a dozen brake jobs and most of them I have had turned down if I feel the distortion of the rotors when applying the brake..If you can't feel anything thru the pedal then they should be allright....They auto stores that turn rotors(NAPA) have the specs on the required thickness and if your rotors are very worn and do not meet the specs then they will refuse to turn them...goodluck...Jim

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James A. Harris